The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Engines may produce hydrocarbons (HC), nitrogen oxides (NOx), and particulates. HC may be filtered by an oxidation catalyst. NOx emissions may be reduced by a selective catalytic reduction (SCR) system. The particulates may be filtered by a particulate filter. In some implementations, the particulate filter may include catalysts in the form of bricks that trap particulates therein. Over time, the particulate filter becomes full and needs to be regenerated to remove the particulates that are trapped in the catalysts of the particulate filter. During regeneration, heat is applied to the trapped particulates to combust the particulates within the particulate filter. After the particulates within the particulate filter are combusted, the particulate filter may resume filtering.
Catalysts of the particulate filter are subject to elevated temperatures during regeneration. Temperature of the particulate filter may not be uniform throughout the particulate filter. In addition to the heat from the exhaust gas, the particulate filter may be subject to exothermic heat released from an oxidizing reaction of HC in the oxidation catalyst that is provided upstream from the particulate filter. Moreover, regeneration of the particulate filter includes oxidizing soots or particulates trapped on surfaces of the catalyst bricks. Oxidizing the soots or particulates releases heat to the surfaces of the catalyst bricks.
Conventionally, exhaust gas temperature sensors are provided upstream and downstream from the particulate filter to monitor an upstream temperature and a downstream temperature of the exhaust gas, respectively. A temperature of the particulate filter may be based on an average of the upstream and downstream temperatures. Control of the regeneration may be based on the temperature of the particulate filter.